UV-VIs Spectrophotometry Study of Escherichia Coli Bacteria and Microfluidic Channel Chip Fabrication For Optical Biosensing Application

One of the most significant foodborne organisms that cause serious foodborne illnesses is Escherichia coli (E. coli). In this work, we demonstrated that the characterization of E. coli suspensions can be facilitated using conventional absorption spectroscopy in the ultraviolet and visible spectral ranges. With increasing concentrations of E. coli, a red shift in the UV-Vis spectra along with an obvious rise in intensity were observed. The results showed that the calculated cell count of E. coli was found in Luria-Bertani (LB) broth in the range of $4.08 \times 10^{8}$ to $1.41 \times 10^{9}$ $\mathrm{CFU} / \mathrm{mL}$. Besides, the optical density was theoretically calculated to be in the range of 1.22 to 3.18. An E. coli suspension in a minute volume needed to be employed, so a microfluidic channel chip was fabricated. To evaluate the suitability and validity of the microfluidic channel for the optical-based measurements, various solutions with different flow rates, including water, acetone, and ethanol, were pumped through the tubes and into the microfluidic channels.